Channel measurement and modeling for VHF bands in typical urban scenarios

In order to empirically characterize the wireless channel propagation for the mobile ad hoc network (MANET) communications in urban environment, extensive wideband channel measurements are performed at 150 MHz on behalf of the very high frequency (VHF) band in Qingdao urban areas. Based on the measurement data and statistical analysis, the path loss exponent, shadow fading standard variations, multipath delay spreads, and frequency correlations are extracted. Two statistical tapped delay line channel models are established for quasi-line-of-sight and non-line-of-sight regions. Numerical analysis shows that in the MANET urban communication scenario, the path loss exponent exhibits a double slope characteristic as the distance increases; the root-mean-square(RMS) delay is 726 ns in the quasi-line-of-sight region and 967 ns in the severely blocked non-line-of-sight region when the cumulative distribution function equals to 0.9; the relevant bandwidths are 700 kHz and 300 kHz in the quasi-line-of-sight and non-line-of-sight regions, respectively. The channel models obtained in this paper can be applied to measure the performance of MANET communication systems in urban areas, and give useful insights for the system design.